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Thursday, March 14, 2013

It's Pi Day! (And how it relates to crochet)

Celebrate Pi!

I ♥ Pi!
As a thread crocheter who loves to make doilies and design in the round, I've come to love pi! I'm not a math person by any stretch of the imagination. If I have to do mental math I'm always off by a factor of 10. Designers all know that eventually it all gets back to the math when working a design.

Stitches per Diameter Inch (SPDI)
I was having a struggle with my very first design until I realized a very important equation concerning pi would help me tremendously. I call it stitches per diameter inch (SPDI), and is probably called by some other terms among other crochet designers and knitters.

To discover what your SPDI value is, work up a circle of dc stitches to 1" in diameter. Count the number of stitches. Example: On a size 1.25 mm hook with size 20 Lizbeth thread, 36 stitches = 1" diameter. Thus, my SPDI is 36 stitches. If I wanted to make a doily that is approximately 15" diameter, the last round would need about 540 stitches.

Knowing your SPDI is helpful if you are working with a different thread size than what a pattern calls for and want to know the final diameter of the doily with the smaller (or larger size) thread. (The math for that is a little more involved and I'll save that for another post.)

Stitches per Circumference Inch (SPCI)
This numeric value is important when making things to wear, like a necklace, hat, sock, sweater, etc. When I designed my first barefoot sandal I needed to know what is the average circumference of an adult woman's ankle. The average is about 11". Using the value of 36 stitches from above as an example:

1 comment:

About the only pie I truly think of is the French silk at our favorite eatery.I use Pi subconsciously I am sure. But I have always worked more artistically than mathematical. I realize it is an important element but don't ever expect me to explain it like you have. I admire those of you who do think like this. It's a gift in and of it's self. Embrace it.

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Shrone Designs

Lori M. Carlson established Shrone Designs in conjunction with her first crochet design. Her favorite medium to use is size 20 thread, in a variety of colors, to create unique and textural designs. She is recognized as a Crochet Associate Professional by the CGOA.